1. Definitions
A. VT - Ventricular tachycardia.
B. Active Site Critical site to deliver ablation energy to cure VT identified by electrical activations.
C. Diastolic - That period of time between two QRS complexes of the electrocardiogram.
D. Ablation - The delivery of destructive energy to the cardiac tissues containing the active site.
2. Field of the Invention
The present invention pertains to a medical system, and more particularly, pertains to cardiac electrophysiology, specifically, ablation of cardiac arrhythmias or modification of the electrical properties of the myocardium. The present invention is also a process for identification of an active site of origin of ventricular tachycardia and for electrode attachment of an endocardial defibrilator lead.
3. Description of the Prior Art
In existing technology, the recognition of the site of the origin of the arrhythmias and the ablation function are performed separately. For ventricular tachycardia, there has been no consensus of opinion as to what electrical activation times constitute the "site of origin". Furthermore, the ablation energy source, whether DC current shock, radio frequency, microwave, or laser, has to be separately redirected by visual means to the site of suspected origin of the arrhythmia.
Arrhythmia ablation is currently performed during open heat surgery or through catheters directed percutaneously through the heart. During the surgical approach, either a hand-held electrical mapping probe or a computerized array of electrodes acquire electrical activation data seeking the site of origin of the arrhythmia. In the percutaneous catheter based approach, a catheter with recording electrodes is positioned in the heart under fluoroscopic guidance.
Following acquisition of electrical activation data, ablation energy is then later delivered by hand-held probes or catheters either in the operating room or in the cardiac catheterizational lab.
In the prior art, the process for identification of the "site of origin" of the arrhythmia was performed with electrical recording procedures designed to map the spread of electrical activation in the heart looking for the site of earliest electrical activation (site of origin). This procedure is carried out by sequentially moving a hand-held electrical recording probe or catheter over the heart and recording the time of arrival of the electrical impulse to that location. This process turned out to be a long and tedious procedure.
Prior art mapping procedures also include a sock multiple electrode array (epicardial), a balloon endocardial electrode array, a single hand-held mapping probe, or a multiple electrode catheter (endocardial) inside a chamber of the heart. These procedures require a skilled surgeon and cardiac electrophysiologist.
The particular concern was the preferred location for an electrode for an endocardial defibrilator. It was not an easy procedure to determine the preferred placement at the active site.
The prior art mapping procedures are capable of reconstructing the spread of electrical activation in the heart, but do not in themselves identify the "active site" of the arrhythmia, can be time consuming, and are separate functions from the prior art ablation procedures.
The present invention overcomes the disadvantages of the prior art by recognizing a particular window or time zone of electrical activation during the diastolic interval of the arrhythmia where ablation energy could be delivered with a high probability for successful cure.